Human herpes virus type six (HHV-6) is a recently-discovered virus with biologic similarities to cytomegalovirus (CMV). Like CMV, HHV-6 is shed in the saliva and female genital tract and may be transmitted to the fetus or newborn. However, the epidemiology and transmission of HHV-6 infection during gestation and early infancy is largely unexplored. This proposal details investigations of the epidemiology of HHV-6 during gestation, the perinatal period, and early infancy. This information is lacking and is necessary to understand the natural acquisition and course of HHV-6 infection. Methods include qualitative and quantitative polymerase chain reaction (PCR), virus culture, serology, and DNA hybridization. Studies described in specific aim one examine the epidemiology of HHV-6 infection in pregnant women followed longitudinally during routine prenatal care at the University Health Center Downtown (UHCD). The presence of HHV-6 in blood, genital secretions, and oropharyngeal secretions will be determined by PCR and culture. Serum antibody levels will also be determined. The periodicity and factors for viral shedding will be determined. Cross- sectional planning and gynecology clinics at UHCD. Specific aim two will focus on congenital transmission of HHV-6. Pregnant women and their newborns will be enrolled at University Hospital at the time of delivery. The incidence and risk factors for congenital infection will be determined. Specific aim three will examine infants longitudinally for HHV-6 infection from birth to age two years during routine visits to the pediatric clinics at UHCD. Cohorts of infants will be analyzed according to the presence or absence of maternal mucosal HHV-6 shedding at delivery. This study may provide new information on the epidemiology of HHV-6 infection during gestation and early infancy, and lead to a better understanding of the epidemiology and pathogenesis of primary infections and potential complications caused by this latent virus.